Any advice on trust after finding his ?

I found out my boyfriend has been watching movies and hiding it throughout our entire relationship. He lied about it, and denied it until he realised that I had found evidence. He has cheated on me before with his ex, one time at the beginning of our relationship, and I have worked hard at coming to trust him again. If he had told me that he watched these films every week that I wasn't with him I would not be as hurt. The fact is he covered something up and lied again. I told him it was me or the films, and he says he will stop watching, but I dont know what to believe anymore. Is it worth the heartache of trying to trust again for someone who might just let you down? My self esteem ually is low from this too, I can't stop thinking he is thinking about the films when we are together.. ladies advice????